#!/bin/sh
# The initramfs images as the mesh builds them (module kernel, novox/hq issue 1977). Run by
# mesh-kernel-initramfs.service:
#
#   initramfs apply [<the microcode drop-in> [<this module's state> [<preset directory> [<boot directory>]]]]
#
# `apply` builds every image again (mkinitcpio -P) when the drop-in differs from the one the images were last built
# with, kept in the state as `initramfs-built`, and records the drop-in only after mkinitcpio succeeded. Later
# kernel upgrades build the images through the distribution's own hook, with the drop-in in place.
#
# A preset that names the default configuration (ALL_config="/etc/mkinitcpio.conf") makes mkinitcpio pass -c and skip
# mkinitcpio.conf.d, so the drop-in is never read: before building, that line is taken out of the preset, a copy of
# the preset kept in the state's taken-over directory (novox/hq ADR 0508 §10's way with a file the mesh did not
# write); any other ALL_config is left and named. After building, every image must hold microcode in its first
# 64 KiB (the early uncompressed archive), else the unit fails and records nothing. The arguments are only for the
# module's tests.
set -eu

dropin=/etc/mkinitcpio.conf.d/mesh-microcode.conf
state='${dir:state}'
[ $# -ge 2 ] && dropin=$2
[ $# -ge 3 ] && state=$3
presets=/etc/mkinitcpio.d
boot=/boot
[ $# -ge 4 ] && presets=$4
[ $# -ge 5 ] && boot=$5

[ $# -ge 1 ] && [ "$1" = apply ] || {
	echo "usage: initramfs apply [<drop-in> [<state directory>]]" >&2
	exit 2
}
[ -f "$dropin" ] || {
	echo "initramfs: $dropin is not there, so the images cannot be built with the microcode hook" >&2
	exit 1
}
if [ -f "$state/initramfs-built" ] && cmp -s "$dropin" "$state/initramfs-built"; then
	echo "initramfs: the images were built with this drop-in, as it was"
	exit 0
fi
for preset in "$presets"/*.preset; do
	[ -f "$preset" ] || continue
	if grep -qx 'ALL_config="/etc/mkinitcpio.conf"' "$preset"; then
		mkdir -p "$state/taken-over"
		cp "$preset" "$state/taken-over/$(basename "$preset")"
		grep -vx 'ALL_config="/etc/mkinitcpio.conf"' "$preset" >"$preset.new" || true
		cat "$preset.new" >"$preset"
		rm -f "$preset.new"
		echo "initramfs: $preset named the default configuration, which skips mkinitcpio.conf.d; that line is taken out, a copy is in $state/taken-over"
	elif grep -q '^ALL_config=' "$preset"; then
		echo "initramfs: $preset sets $(grep '^ALL_config=' "$preset" | head -n 1), so the microcode drop-in may not be read; left as it is"
	fi
done
if ! mkinitcpio -P; then
	echo "initramfs: mkinitcpio failed; nothing recorded, the next start tries again" >&2
	exit 1
fi
missing=
for img in "$boot"/initramfs-*.img; do
	[ -e "$img" ] || continue
	if ! head -c 65536 "$img" >"$state/image-head.tmp" || ! grep -aq 'kernel/x86/microcode/' "$state/image-head.tmp"; then
		missing="$missing $(basename "$img")"
	fi
done
rm -f "$state/image-head.tmp"
if [ -n "$missing" ]; then
	echo "initramfs: mkinitcpio ran, but no microcode is in the early archive of:$missing; nothing recorded" >&2
	exit 1
fi
cp "$dropin" "$state/initramfs-built.new"
mv "$state/initramfs-built.new" "$state/initramfs-built"
echo "initramfs: the images are built with the microcode drop-in"